How many? What time do you plan to leave the Fair Grounds? I assume--perhaps wrongly--that you would be going back to the hotel and cleaning up? If it is only a couple of people then getting in even at Commander's should not be a problem. Lots of people have reservations and get too burned or drunk or become too tired to make it and I've seen people walk in at 7:00 without much if any waiting. Just judging by Bayona on your list it seems you are not averse to making an effort.

If you are staying in the CQ or CBD dress nicely and hit some places. Some are used to taking walk ins. NO is a city where picking a restaurant at random has a very high chance of getting you a good meal although it may not be your first choice of meal.

If you are staying in the FQ, you can go back to your hotel, get cleaned up and walk over to Roux on Orleans, in between Royal and Bourbon streets. Restaurant is in the Bourbon Orleans hotel. Quiet good and virtually unknown.Good for breakfast and dinner....have not tried their lunch.